Reliance on a North American personality test is hampering applications by the Director of Public Prosecutions to keep allegedly dangerous sex offenders in jail as WA’s Supreme Court judges lead a national backlash against the psychometric tool.

The ‘Static-99‘ test developed by US and Canadian researchers purports to predict a sex criminal’s chances of reoffending.

The DPP frequently uses Static-99 to determine if former offenders whose jail terms have expired remain a high risk to society, and should therefore stay in jail.

However, in a string of Supreme Court judgements since 2007 judges have expressed grave doubts about the test.

Last Friday, Justice John McKechnie suggested the main reason the DPP applied to keep sex offender Leslie Fred Free behind bars after his five-year jail term expired was his ‘high-risk’ score in the test.

“This application highlights the limitations of Static-99,” his written ruling explained.

“The respondent will remain at a statistical high risk of offending under Static-99, no matter what interventions occur and how much he changes his lifestyle, because it takes no account of dynamic factors.”

Static-99 is used more than any other test, and in many countries, to measure a sex criminal’s chances of reoffending.

Justice McKechnie concluded that “uncritical acceptance” of its results negated the purpose of treatment programs offered in prisons.

As a growing band of legal and psychological researchers across Australia queries the use of Static-99 for sentencing, judges in other states have to date accepted the results apparently without question.

In July at a Victorian legal aid seminar, Monash University law Professor Bernadette McSherry said WA judges were the only ones in Australia to openly criticise the test.

“Many of the Western Australian cases deal with indigenous offenders and it may be that, as a result, there has been a greater skepticism shown towards the relevance of North American scales in such instances in comparison with other states with smaller indigenous populations,” Professor McSherry suggested.

Her paper spotlighted four other cases – in 2007 and 2008 – where Static-99 was slammed by Justice McKechnie and two other West Australian Supreme Court judges.

In two of the four cases, the DPP’s application was thrown out of court.

A DPP spokeswoman said Static-99 was just one of several risk prediction tools used in arguing for dangerous sex offender applications.

She added that for the three cases that the DPP lost, the use of Static-99 was not the only reason for the judges’ decisions.

The spokeswoman said that in the Free case, as with all significant decisions, the DPP was considering whether an appeal would have merit.